The statements in this section merely provide background information related to the present disclosure and may not constitute the prior art.
MPEG (Moving Picture Experts Group) and VCEG (Video Coding Experts Group) developed an improved and excellent video compression technology over the MPEG-4 Part 2 and H.263 standards. The new standard is called H.264/AVC (Advanced Video Coding) and was released simultaneously as MPEG-4 Part 10 AVC and ITU-T Recommendation H.264.
The H.264/AVC (hereinafter, referred to as “H.264”) standard generates a residual signal by performing an intra prediction and/or an inter prediction in the unit of macroblocks having various types of subblocks, transforms and quantizes the generated residual signal, and encodes the residual signal. The inter prediction, which is one of the methods of compressing a video by removing the temporal redundancy between frames of the video, estimates motion of a block to be encoded (hereinafter, referred to as “a current block”) in the unit of blocks by using one or more reference frames, generates a predicted block of a current block based on a result of estimated motion, and compensates the motion.
In a typical inter predictive encoding, when a motion of a current block is estimated for generating a predicted block, the typical inter predictive encoding searches for a block which is most similar to the current block within a determined search range of a reference frame by using a predetermined evaluation function. When the block similar to the current block is found, the typical inter predictive encoding generates the predicted block by using a corresponding block and encodes and transmits only a residual signal, which is a difference of pixel signals of the current block and the predicted block, thereby improving the compression ratio of data.
However, in the event where the motion is compensated according to the aforementioned typical inter predictive encoding, if a local illumination change or a viewpoint change occurs in each frame, it is difficult to perform efficient encoding. That is, when a pixel value is increased due to the occurrence of the illumination change or the viewpoint change at the position of a current block, compensating the motion with a predicted block generated by the existing method causes a size increase of the residual signal, resulting in deteriorated efficiency of encoding.